The present invention relates generally to a transmission antenna for flow meters and, more particularly, to an antenna for an indicating meter positioned beneath the ground such as used by utilities and municipalities to meter consumption of natural gas, water and electricity.
Commodities such as natural gas, water and electricity are routinely delivered to commercial and industrial establishments and residences by piping networks or electrical lines (as the case may be) operated by utility companies and municipalities. For billing purposes, such commodities are xe2x80x9cmeteredxe2x80x9d at the point of consumption. That is, the network line or xe2x80x9clateralxe2x80x9d extending to the establishment or the residence includes a meter indicating how much of the commodity has been consumed in a period of time and the commodity customer is billed accordingly.
It has been estimated that there are about 600 million utility meters installed worldwide. It has also been estimated that there are about 270 million utility meters in the United States and that about 150-160 million of those meters are used for gas and water. Only a very small percentage of utility meters are configured to be read remotely.
In fact, most such meters are read visually by a person walking on site to actually view and manually record the information displayed on the meter dial. There are a number of disadvantages to this form of meter reading. One is that it is enormously labor-intensive. The overhead costs to a utility or municipality for xe2x80x9cwalk-byxe2x80x9d meter reading are very substantial.
Another disadvantage of such form of meter reading is that the person reading meters is subjected to various forms of hazard, e.g. deep snow, barking (and perhaps biting) dogs and the like. And it is not unheard of that a customer intentionally keeps a ferocious dog in the hope of preventing the meter from being read.
Still another disadvantage is that property owners, especially residential owners, prefer that meter readers not walk on the property. Sometimes, there is a risk that however careful, the meter reader will trample flowers or ornamental shrubs.
In recognition of the disadvantages of walk-by meter reading, meters have been developed which can be read remotely. Such meters are configured as transponders and include a radio transmitter. When the meter is xe2x80x9cinterrogatedxe2x80x9d by a radio signal from a remote location, the meter responds by transmitting a signal encoded with the meter reading.
In each of the remote meters, an antenna assembly is connected to the meter to transmit the measured commodity use to the remote reading device. Examples of such systems are shown in U.S. Pat. Nos. 5,298,894 and 5,659,300. In the systems shown in the above mentioned patents, the meter itself is positioned beneath ground in a pit that is covered by a metal pit lid.
In each of these remote meter reading systems, an antenna is shown as extending above the top surface of the pit lid such that the radio frequency signal generated by the antenna is transmitted from above the pit lid. Typically, the pit lid is formed from a metallic material, such as iron, that inhibits the transmission of a radio frequency signal therethrough.
A significant disadvantage of such systems is that the antenna enclosure extends above the pit lid. Since meter pits can be located in a sidewalk, street or yard of individual user, the protruding antenna enclosure can be contacted by either a vehicle or a pedestrian. If the antenna enclosure is contacted by a vehicle, the antenna enclosure can be damaged and must thus be replaced to ensure proper operation.
Therefore, a need exists for an antenna enclosure that is flush mounted with the top surface of the pit lid to prevent the antenna enclosure from being damaged by contact with a vehicle or other device. Further, another object of the present invention is to provide an antenna enclosure and pit lid such that the antenna enclosure can be positioned beneath the pit lid and transmit the radio frequency signals through the pit lid. Further, it is an object of the present invention to configure the pit lid to receive the antenna enclosure of the invention to allow the radio frequency signals generated by the antenna to be transmit to a remote reading device.
The present invention involves an antenna enclosure and mounting arrangement for mounting a radio frequency antenna on a pit lid. The pit lid covers a pit enclosing a commodity meter.
The antenna enclosure of the present invention includes an antenna housing having a tapered upper support portion. The tapered upper support portion angles outward away from the cylindrical main body of the antenna housing to define an upper surface having a greater diameter than the cylindrical body portion. The upper support portion of the antenna housing contacts a similarly tapered surface that defines an opening within the pit lid.
When the antenna enclosure is mounted within the pit lid, the top surface of the antenna enclosure is flush with the top surface of the pit lid. The actual antenna contained within the antenna enclosure is thus positioned slightly beneath the top surface of the pit lid. When the antenna enclosure is mounted on the pit lid, the tapered surface that defines the opening within the pit lid allows for an increased angle of transmission from the antenna, thereby increasing the effective range of the antenna.
The antenna housing of the invention is secured to the pit lid by a compression fitting that surrounds the cylindrical main body portion and contacts the bottom surface of the pit lid. In this manner, the antenna housing is securely held within the opening formed in the pit lid.